Getting some oil coming through under spark plug #2. possibly #3 also.
Changed the plugs in January.
I tightened it down the other day and seeing the leakage and heard a nice crack. Runs fine though.
Wonder if I broke the ceramic portion of plug. Was hoping the noise I heard was the spacer washer pressing into place.

Maybe I over-torqued ? not sure?

Hope I'm not looking a heli-coil repair here.
How much shop time is a heli-coil repair for plug?

Anyone have any leakage issues before through plug threads?

Adipose

 

Whydid you break the gasket lol. I suppose its the problem.



Buy another sparkplug and this time! add some lube for the gasket that way you don't overheat it and tear it when torquing.

It's 99 cents at autozone or advanced auto at the checkout counter.

Also it's good to add for when your taking them off.

 

Just to make sure, how much did you use the wrench? You're only supposed to hand-thread them all the way, or as much as you can, and then cinch them with the socket. They are very easy to cross-thread.

Second of all, are you sure the valve cover isn't leaking to make it look like the oil is coming out of the spark plug hole? It's easy to make that mistake. Oil shouldn't be in the cylinder anyway. Even on an old, worn engine, there wouldn't be enough leaking past the rings and valve guides to actually start seeping out of the spark plug hole. It would take a LOT of oil to do that. I guess it could happen, but my money is on your valve cover gasket seeping down.

 

I don't believe the inline six motors used gasketed spark plugs. I believe they use a tapered seat instead. This is why you hand-tighten and then cinch tight.

Autocraft plugs would back out of my 1988 inline six after just a hundred miles or so. I went through several sets, and some would be as much as a turn or two loose, and the plug holes were all oily. Switching spark plug brands solved the problem in that motor (I used regular Champion copper plugs; any other brand might be fine.). Maybe that motor just wasn't taken care of well by the previous owner.

Never had problems with plugs backing out in the '76. Truck came with Motorcrafts in it, and they were good and tight.

 

Give this man a cigar! If you're using gasketed plugs that's your problem.

 

I installed Motorcraft plugs. The model # escapes me right now, but they were cross-referenced and double & triple checked before purchase.
I hand tightened them and seated further w/ socket wrench firmly.
Valve cover gasket was replaced last year by a very good local shop.
I don't think i recall a gasket on those Motorcrafts plugs.
Wonder what's up?

 

I'm not sure of your problem but it's a good idea to use anti-sieze on the plugs threads, another tip is to use a piece of vacum line and push the end of the plug in it then thread it into the head using the vacum line has a handle, this avoids any chanch of cross threading it as the vacum line will twist free before you can ruin a thread.

 

????So which is it?

 

no washer or gasket on spark plug for those. They use tamper. My truck have 4.9L it use tamper spark plug it seem no leak it work fine. replace 2 times due I put too much miles. They would last 30,000 miles then start lose little performance and little hard start due foul. But cheap is replace 6 spark plugs then you see little increase mpg like average 15 but boost to 16 to 17 mpg.

 

Silver Streak:
The motorcraft plugs I bought do not have gaskets. Think i gave to much credo to ol' Nicholas1990! LOL! and assumed he knew. whoops. gotta watch that in the future . LOL!

So not sure whats up yet at this point but I know oil is getting through there. I'll buy a few new plugs use thread anti-seize on them and give it another go.

 

How do the head threads and plug seat look? Corroded? Clean? Do the plugs screw in smooth and easy, or do you have to force one or two? What color are the insulators and electrodes on a well-used set in your truck? Rich? Lean? Running hot? Also, what year truck do you have?

Silver Streak-
Thanks! In lieu of a cigar, I'll take a glass of the smokiest, dankest scotch you've got. Straight, please, just like my motors.

 

BigBlue88- Head threads and plug seat look dirty. looks like it's been leaking previously before i noticed oil coming through. Gunk accumulation adjacent to spark plug area. Did not want to get that crap into the engine block so cleaned it as best I could when old plugs were still installed. The plugs screw in somewhat smooth, some easier then others but all doable to start threading by hand. A well used set of plugs shows clean insulators w/ whitish/grey electrodes. I think she's running hot. Not sure why. Time to flush radiator you think? Radiator not using fluid this winter but was last summer. But at that time I wasn't sure if I was loosing fluid or If I was catching up on topping off. Basically saying it took me about 3 or 4 times to fill up radiator fluid res. last summer when I noticed it was low. I love the truck more and more and am paying more attention to her now than last summer.

 

Also wondering what the heck I heard 'Crack' when i tightened down the spark plug a few weeks ago. Been avoiding pulling the plug until i get some replacements. Also being a bit gun-shy as it's running as usual and dont want to get into a jam and have the truck down. I'm more the type to get long term fixes fixed but dished out 300.00 for throttle body repair on my wifes '04 Escape last week...

 

Truck is a '93 F150 4.9 extra cab short bed 4WD w/ 5 speed M05 manual transmission.
Getting about 16.15 mpg's to work and back and 10-12 mpg's when towing my boat around W WA on fishing trips.

 

Your truck is mechanically very similar to my previous '88 (F150 2WD, M5OD, EEC IV OBD1), and has identical symptoms- dirty, oily plug threads on all cylinders and trouble screwing the plugs in. Got 17+MPG commuting in rush hour traffic until it started throwing codes for a faulty EGR (no EGR flow, running lean), including a stumble off idle. I now know everything there is to know about EEC IV OBD1 EGR controls. The vacuum solenoid valve that controls the EGR valve had worn out. Ford doesn't make them anymore, nor do they sell them. Some dealers may still have stock, but it's few and far between. I managed to adapt a GM part which worked well enough; I've got an old thread about that which I can dig up. Fixed the EGR problem, and my mileage went down to 15 or so, but with no off-idle stumble. Your hot/white plugs are probably due to a mild lean condition caused by an EGR which is failing, but not quite bad enough to throw codes. Ford Fuel Injection » How To Run a Self-Test is a great resource for pulling computer codes with a paperclip, and they've got very descriptive pages on what the codes mean. Do it once or twice, and it becomes second nature.

There's probably some metallurgical factors in the plug thread corrosion; perhaps the cast iron expands more than the alloy plug threads Ford used as OEM on these EEC IV TFI ignition motors, and some leakage and corrosionresulted. I agree with not wanting to get junk into the combustion chambers. I'm not sure what the right way to clean those out is.

You heard a "crack" when you tightened down #2? I've broken the #2 plug on every new set I've put in. #2 was right next to a cast alloy accessory mount on my '88, and it's a really tight squeeze past to the plug. My 76 has the ignition coil mount right next to #2, and I didn't think to just bend the sheetmetal mount until I'd snapped another $6 spark plug. If the inner electrodes are at all touching, you'll still get spark and the engine will still run well enough. I drove my '88 for a full tank of gas (600 miles- dual tanks) with a completely severed plug held together by the rubber plug boot alone. Hopefully none of your plugs are cross-threaded. I'd check the #2 real carefully when you re-install.

Autolite plugs leaked continuously and would come loose in the 88. Champions didn't. Never tried Motorcraft due to cost and four Advance stores and three NAPAs being closer than the nearest Ford dealership. Autolites seem fine in my 76, except for radically varying plug resistances after a thousand miles or so. I don't like Autolites, but plug brand loyalties are a holy war. When I was a kid playing with junk lawnmowers, an old Champion plug would almost always work, but AC or Autolites usually didn't (probably why the mower was tossed).

Chances are your thermostat is stuck open or disintegrated instead of stuck shut. These engines are meant to work and run cold in regular driving. Both my trucks ran cold in the winter, and I'd block half the radiator with cardboard just to get them to warm up within 5-10 miles of driving. The 88 got wrecked before I could do anything else. I replaced the thermostat in the 76 with an OEM part from Advance Auto, and it warms up quick in the summer, slower in the winter. Original part was completely disintegrated. I still run some cardboard during the winter because of the oversized towing radiator in my truck.

EGR and thermostat issues don't surprise me on a 15 year old truck. I'd look at those first, and maybe replace plug #2. My 88 was 18 years old when I had to deal with those same problems, and had probably existed for a while.